Ulla Klein

Sensillum-lymph proteins from antennal olfactory hairs of the moth Antheraea polyphemus (Saturniidae)

Abstract The soluble proteins in the antennae of the male and female saturniid moth Antheraea polyphenus were analyzed by isoelectric focusing in miniature ultrathin-layer polyacrylamide gels and by microgradient PAGE (μPAGE). Different preparations of sensillum lymph from male antennal olfactory hairs (isolated sensillum-lymph droplets, rinsing solution from isolated hairs) and homogenates of male and female antennae were compared. The pheromone-binding protein, PBP, and the pheromone-degrading sensillar esterase, SE, were detected only in male antennal preparations. Isolated sensillum lymph exhibited two proteins in Brilliant Blue staining: (1) the PBP appeared as a double band with a relative molecular mass of M r (α-lactalbumin); (2) an oligopeptide was detected as a faint band at a very small molecular mass ( M r ⪡ 14,000 ). The PBP in isolated sensillum lymph was identical to the PBP in the rinsing solution of isolated hairs and in male branch homogenates. Purified PBP from branch homogenates showed a third slightly smaller band. In reducing SDS-μPAGE, the denatured PBP from all preparations showed only one band at a M r of 14,400. The isoelectric point (pI) of the PBP was 4.7. The PBP appeared to be a non-glycosylated protein. Glycoproteins were present in the hemolymph in different patterns in both sexes. The concentration of PBP in sensillum-lymph droplets was ≈ 10 mM, corresponding to a total amount of ≈9 μg/55 μl sensillum lymph in one antenna. A third protein in the sensillum lymph, the sensillar esterase, was only visible by enzyme staining and had a M r of 55,000 and a pI of 3.0. The integumental esterases found in male and female antennae had a M r of 65,000, pI 5.85, and M r 90,000, pI 5.0. From body scales of both sexes, esterases in the range of M r 100,000 were solubilized by 0.01% Triton buffer and could be demonstrated in μPAGE.

Sensilla of the cricket palp

SummaryOn the distal segment of the maxillary palp of the cricket Gryllus bimaculatus there is an extensive multimodal sensory field comprising approximately 5000 sensilla of nine morphologically distinguishable types: three types containing pores in their walls (5% of the total), three types with a pore at the tip (65%), and three types lacking pores (30%). The approximately 27,000 axons of their sense cells join in the distal palp segment to form two nerves. On the slightly smaller sensillum field on the tip of the labial palp, the same sensillum types are found in comparable density and proportion. By analogy with sensilla of which both structure and function are known, the structure of these three groups of sensillum types suggests that they function as olfactory, contact-chemoreceptive, and/or mechanoreceptive sensors. Moreover, the positioning of the sensilla on the tip of the palp is appropriate to these functions. The cuticle of the palp tip is elastically deformable; all sensory hairs are fixed via a special, presumably flexible socket suspension. These structural features could be an adaptation to stresses encountered during tactile activity of the palp.

Dendritic membrane from insect olfactory hairs: isolation method and electron microscopic observations.

Summary1.Sensory hairs from antennae of male saturniid moths (Antheraea polyphemus) were separated while deep-frozen by shaking antennal branches with glass beads. The hairs were collected through their differential adhesion to the surface of a petri dish. The yield, determined by the length of the isolated hair fragments, was about 38% of the estimated total hair length per antenna.2.The dendritic membrane was separated from the hair fragments by centrifugation through Sephadex and further purified by ultracentrifugation in sucrose buffers.3.Transmission electron microscopy was used to monitor the steps of the hair and membrane isolation and to investigate the membrane pellet.4.Some membrane vesicles bound cationized ferritin, thus indicating a negatively charged cell surface coat.5.Negatively stained membrane vesicles exhibited a pattern of repetitive substructures irregularly distributed over the vesicle surface. The units had a diameter of about 3 nm and a maximal density of 30,000/µm2.

Antennal sensilla of Magicicada cassini (fisher) (Homoptera : Cicadidae): Fine structure and electrophysiological evidence for olfaction

Abstract The antennae of Magicicada cassini (Homoptera : Cicadidae) (3–4 mm long) look similar in both sexes and consist of scape, pedicel, and a 5-segmented flagellum. The length of flagellar segment 1 varies independently in relation to head size and is slightly longer in females (0.96 mm) than in males (0.89 mm). The ventral side of flagellar segment 1 is covered with sensilla coeloconica comprising about 60 large, 10 medium-sized, and 35 small sensilla with pit diameters of 8–24, 6–10, and 2 μm, respectively. The large and the medium-sized sensilla coeloconica are multiporous single-walled sensilla with pore tubules, containing branched entangled dendrites from 3 receptor cells. The small sensilla coeloconica, situated primarily at the outer border of the sensillum field, are no-pore sensilla with inflexible sockets. They contain 2 unbranched dendrites extending to the tip of the peg, and 1 dendrite reaching to its base and wrapping around the other 2 dendrites. Small sensilla campaniformia (cap diameter 3 μm) are aligned at the outer border of the sensillum field and continue all along the flagellum. Up to 3 olfactory receptor cells were distinguished on the basis of their nerve impulse amplitudes through extracellular electrophysiological recordings from sensilla coeloconica, presumably large ones. They respond to stimulation by cyclic terpenoids with different but highly overlapping reaction spectra, and react selectively to structural variations of the molecules. No responses to CO 2 , temperature or moisture were recorded.

The articulation of cricket palps: morphology and movement patterns in behaviour

ABSTRACT. The morphology of the palp joints in Gryllus bimaculatus DeGeer is described in the context of their use in various behavioural situations. Two patterns of movements are distinguished: the goal‐directed movement of each individual palp, as seen during grooming and food intake actions, and the rhythmic probing movement of the two maxillary palps together during exploratory behaviour and walking. Their details were studied by single frame analysis of video and cine records. The functional characteristics of the maxillary palps with regard to the dimensions of space within which they move in these patterns (‘operational space’) and the potential sensory stimuli they receive (‘reception space’) are compared with those of the antennae and discussed from the viewpoint of division of labour.

FUNCTIONAL MORPHOLOGY OF PALP SENSILLA RELATED TO FOOD RECOGNITION IN GRYLLUS BIMACULATUS (SALTATORIA, GRYLLIDAE)

Peculiarities of the fine structure of three types of contact chemoreceptor on the tips of the maxillary palps of the cricket Gryllus bimaculatus De Geer, as observed by electron microscopy of serial sections, are described. At the tip of one of these is a complex system of slits and channels partially filled with electron‐dense material which is the stimulus conducting system between the external medium and the chemosensory dendrites. In other receptors there is an accessory dendrite with a tubular body, that ends proximal to the lower edge of the hair shaft. Various structures are discussed in relation to transduction of the mechanical stimulus, and to possible protection against excessive strain.